The invention relates to a filter that may be reused many times without damage to remove dirt and other contaminants from high temperature gases generated by burning propellants, and thus prevent the contaminants from fouling movable members exposed to the gas.
Present day military aircraft of high performance capability require external stores to be displaced from the aircraft at high velocity in order for the stores to properly leave the aircraft flow field without damage. This is generally accomplished by ejector racks, missile launchers and the like, using explosive cartridges that create high temperature gases as an energy source. The high temperature gases act on piston actuated devices that in turn eject the stores at the desired high velocity. The propellants burnt in conventional cartridges generate gases of a temperature in excess of 4500.degree. F. Unburnt propellant, residue from igniters, oxides from the cartridge cases, and erosion of the breech all create particles which act to ultimately foul the ejector rack piping and the ejector guns or the like.
In the past, the residue of these particles has been removed by periodic disassembly and cleaning of the rack and the like, which is costly and affects operational availability of the rack. On the other hand, the failure to carry out periodic cleaning affects reliability, since the residue buildup can cause the rack to fail to operate properly. Various solutions to this problem have been sought, including attempts to arrive at a clean burning cartridge that does not provide contaminants, and attempts to design a filter to remove the contaminants from the high temperature gas path before the gas acts on the piston actuated devices. A sufficiently clean burning cartridge is yet to be developed, and filters that may be reused through a large number of operational cycles have not been satisfactorily obtained because of the destructive effects of the high gas temperature on the filter.